The invention relates to a method and a device for monitoring the transport of flat copies, for example copies separated from a material web in a folder and to be folded longitudinally and/or transversely therein.
The published European Patent Document EP 0 847 857 A1 is concerned with an adjusting device of a traversing mechanism disposed upline of a cylinder in a rotary printing machine. On the traversing mechanism, a measuring device is displaceable axially with respect to the circumferential surface of the cylinder by a holder. For adjusting the alignment of the traversing mechanism with respect to the cylinder in a manner that is accurate, uncomplicated and can be automated and has an interchangeable direction of adjustment, the holder can be coupled to an opto-electric auxiliary adjustment device. The auxiliary adjustment device has an optical element that projects a light beam onto the cylinder and at least one optical receiver, which receives a light beam reflected from the cylinder. The optical receiver includes an opto-electronic sensor which, in conjunction with evaluation electronics, is suitable for detecting the position of the reflected light beam on the sensor.
This device is primarily used to align an optical measuring device that scans the surface of the cylinder.
The European Patent 0 753 409 is concerned with a sheet printing machine having a delivery on the upper side of which continuously delivered sheets are to be deposited. It is intended to make possible, in a manner which is simple and does not adversely affect the formation of a sheet pile, the use of a traversing measuring device for scanning a printing control strip applied to the leading edge of the sheets. For this purpose, the measuring device, which is movable on a traversing mechanism, has so-called sheet high-holders assigned thereto, which prevent sheets conveyed while a measuring operation is being performed from being deposited on the upper side of the stack.
With this device from the prior state of the art, however, a conveying path traced by the copies, somewhat through a folder, cannot be detected reliably.
U.S. Pat. No. 3,815,895 discloses a paper-jam detection system for folders which are arranged downline of a web-fed rotary printing system. Photocells disposed within the folder at selected locations detect both copies which are erroneously absent and copies which are erroneously present along the conveying path through the folders. A time-sequence control unit, which operates in synchronism with the folder, generates signals which initiate detection as to whether a copy to be expected at a specific location is actually present there and whether a copy not to be expected at a specific location on the conveying path actually does not arrive at this location. The signals from the photocells are logically linked with those from the time-sequence control unit, and fed to a logic circuit which, if necessary or desirable, stops the folder. The system also detects a failure of one of the photocells in the paper-jam detection system.
It has been found that not only paper jams which occur at full operating speed in a web-fed rotary system cause drastic consequences in the folder and long down times of a rotary printing machine, but also, paper jams which occur even during the threading of the web or at creep speed of the rotary printing machine, or due to misguiding the paper can at least cause avoidable delays during run-up or acceleration of the rotary printing machine. During the threading of the web or at creep speed of the rotary printing machine, very high torques can occur, mechanical settings of grippers, cylinders or similar components in relation to one another can be indefinite, while the attention of the pressman can be directed to other work necessary within the context of a new job set-up.
It is accordingly an object of the inventions to provide, in accordance with the invention and in view of the outlined advancements in the prior art and the indicated technical problems, a device for monitoring the transport of flat copies or, in other words, a paper-run monitoring system, which is responsive to irregularities in the copy transport at slow paper conveyance speeds.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a method of monitoring the transport of flat copies along transport paths in a folder, which comprises selecting sensors for detecting at least one of the presence and the absence of copies, depending upon the folding mode of the folder; determining by transmitters the number of copies that have entered the folder, and comparing the number of copies present in the folder with the number of copies detected by the sensors.
In accordance with another mode, the method of the invention includes validating the sensors based upon the progression of the copies along the transport paths, in accordance with the folding mode of the folder.
In accordance with a further mode, the method of the invention includes performing a validation, at the start of the transport of the copies through the folder, by sensors upland to the transport start, after a few copies have been conveyed to the folder.
In accordance with an added mode, the method of the invention includes performing a validation of sensors disposed farther downline along the transport path than the first-mentioned sensors, after a large number of copies have been transported into the folder.
In accordance with an additional mode, the method of the invention includes assigning a transmitter to a cylinder, and determining by the transmitter the number of copies transported into the folder.
In accordance with yet another mode, the method of the invention includes determining the number of copies transported into the folder, by a transmitter assigned to a drive of the folder.
In accordance with yet a further mode, the method of the invention includes transmitting the determined number of copies to a monitoring and evaluation unit.
In accordance with yet an added mode, the method of the invention includes, in accordance with a selected folding mode of the folder, determining for each sensor the ratio between the number of copies that have entered the folder and the number of copies respectively counted at the sensor position.
In accordance with yet an additional mode, the method of the invention includes, for each sensor position, determining a maximum permissible difference between the number of copies that have entered the folder and the number of copies that have actually appeared at the position of the respective sensor.
In accordance with still another mode, the method of the invention includes performing the validation of the respective sensors based upon the attainment of a minimum number of conveyed copies at the respective position of the sensors.
In accordance with still a further mode, the method of the invention includes performing the comparison between the theoretical number of copies and the number of copies actually detected for each sensor position in real time.
In accordance with another aspect of the invention, there is provided a device for performing a method of monitoring the transport of flat copies along transport paths in a folder, comprising sensors grouped as sensor pairs, respectively, having a transmitting part and a receiving part.
In accordance with another feature of the device of the invention, at least one of the material web and the copies are conveyable in a conveying plane, and the receiving and transmitting parts of the sensors are arranged on opposite sides of the conveying plane.
In accordance with a further feature of the device of the invention, the transmitting part is formed as a proximity switch.
In accordance with an added feature of the invention, the device includes a transmitter assigned to a drive of the folder and formed as a rotary encoder.
In accordance with an additional feature of the device of the invention, a then current folding mode of the folder is determinable by the position of the folding components on a paper-carrying cylinder, and further included is a monitoring unit to which the then current folding mode is transmittable.
In accordance with another aspect of the invention, there is provided a folder for a rotary printing machine, for processing material webs, the folder being capable of operating in at least two folding modes, and having its own drive, comprising a monitoring unit, by which, in accordance with a respectively selected folding mode, copy conveying paths are able to be validated by respective sensors assigned to the copy conveying paths, based upon progressions of the copies through the folder, and the number of the copies present in the folder are able to be compared with the number of copies that have entered the folder.
In accordance with a concomitant aspect of the invention, there is provided a rotary printing machine having a folder that is capable of operating in at least two folding modes, and having its own drive, comprising a monitoring unit, by which, in accordance with a respectively selected folding mode, copy conveying paths are able to be validated by respective sensors assigned to the copy conveying paths, based upon progressions of the copies through the folder, and the number of the copies present in the folder are able to be compared with the number of copies that have entered the folder.
The advantages that can be achieved by the foregoing modes and features of the invention are many and varied. Thus, by using the method according to the invention, folders can be incorporated significantly faster into the paper run at creep speed of the upline rotary printing machine, because misrouted copies in the folder can be detected immediately and can lead to the folder drive being switched off. This constitutes an effective safeguard for mechanical folding components which are installed in an, as yet, undefined way in relation to one another and which, at creep speed, could be considerably damaged by the high torques occurring thereat. Both at creep speed of the rotary system and also during the paper threading phase, the pressmen can devote their attention to further necessary pre-settings, an incipient paper jam or the misrouting of a copy will then be detected automatically.
In a further refinement of the method upon which the invention is based, sensors in the folder are validated, based upon the progression of the copies along the conveying path, depending upon the folding mode of the folder. The validation, i.e., the declaration of validity of a sensor signal, which can be performed electronically, in the case of the sensors located at the start of the copy conveying path, is carried out only after a few copies have entered the folder, after which the relevant sensor can detect a copy at the very earliest, in accordance with the folding mode set with the preselected transport path. The validation of sensors arranged earlier in the copy transport path is carried out after a lower, pre-settable number of copies, while the validation of sensors arranged later in the copy transport path is carried out after a larger number of copies have entered the folder, corresponding to the distance extending as far as the validating sensor.
The limiting values which permit the validation can be predefined at the monitoring unit and stored there, so that they are always currently available for the necessary calculations.
The validation of the sensors corresponding to the selected folding mode along the conveying path of the copies that is associated with the folding mode ensures the reliability of the signals transmitted by the sensors to the monitoring unit. The determination of the number of copies which have entered the folder is carried out, for example, by transmitters assigned to the cutting cylinders or revolution counters assigned to the drive motor of the folder. Depending upon the selected length of the cut, it is thus possible for the number of copies transported into the folder to be determined individually.
In the monitoring unit, according to the method of the invention, the difference between the number of copies detected for each validated sensor and the number of copies located in the folder is determined continuously, it being possible for a maximum permissible difference to be predefined at the monitoring unit. This difference can be predefined in accordance with or based upon the printing material parameters, copy thickness and values from experience, in order to set up the monitoring system suitably for the job.
The sensors required in order to perform the method according to the invention are preferably pairs of sensors which comprise a transmitting and a receiving part. These are spaced apart from one another, with the conveying path of the copies running between the transmitting and receiving parts. The transmitters assigned to the cutting cylinders or the drive of the folder can be configured, for example, as proximity switches or encoders, such as rotary encoders, which for each revolution of the relevant unit transmit a counting pulse to the monitoring unit, the pulses being added therein.
By the modes and features of the invention, it is preferably possible to monitor folders which are arranged downline of a web-fed rotary printing machine, the monitoring unit validating the sensors required in accordance with the copy conveying path necessary for the selected folding mode, and the sensor signals, validated in this way, for the number of copies being compared with that number which has entered the folder. From this comparison, performed in real time, a switch-off condition in the folder and/or for the entire rotary printing machine can be derived.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method and device for monitoring the transport of flat copies, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.